I decided to write a mini-glossary for people who may not understand some of the terms and acronyms that we're throwing around in the forum. It looks like we have a few people who have never owned an MP3 player before, so maybe this will be helpful.

DAP (Digital Audio Player): This is a more correct term for what people usually call an "Mp3 player" because not all DAPs can play MP3s (most can though), and lots of them can play other types of audio files in addition to MP3s

Flash memory: A type of digital memory. Some players use flash memory to store info - it's the same thing that USB thumb drives use. It has no moving parts to get damaged and it’s very small, but compared to other data storage methods (like hard drives, CDs) it's very expensive but prices drop every day. Important to note that they wear out after data is written to then after numerous years of writing/erasing to it. They last longer if you are not constantly erasing and putting new data on your player. I've seen about 10,000 write cycles quoted as an approximate life. Remember, nothing lasts forever). Also look here.

Gigabyte: 1024 megabytes

Hard Reset: Many players have a facility to stop/reset the device when they have crashed or entered a temporary non-working state. Usually reverts the device to the default factory settings and condition. Usually results in the permanent loss of all user installed data on the device.

HDD (Hard Disk Drive): Just like the spinning disks stuck deep inside your computer (the C: drive on Windows; various names on other systems)..but smaller! These little hard drives come in 1" and 0.8" sizes. The latter are called micro hard drives. The regular iPod and the iPod mini are the best-known players that use them. The Creative Zen players do too. They come in larger capacities...generally around 20-60 GB than flash memory does.

Kilobyte: 1024 bytes

Lithium-ion Battery, Lithium-ion Polymer battery: Probably the two most widely used types of batteries and battery technology in MP3 players, lithium-ion batteries and lithium-ion polymer batteries in MP3 players are—unlike AAA and AA batteries. These are typically not replaceable by consumers when the batteries fail to hold an adequate charge. Unlike nickel-cadmium batteries, lithium-ion batteries and lithium-ion polymer batteries do not have to be discharged before recharging. Further information at the Battery University.

Megabyte: 1024 Kilobytes

Memory Effect/Voltage Depression: The reduction of a battery's capacity or voltage if it is charged when it is partially charged already.

NiMH/Nicad Batteries: A type of battery technology used in portable devices.

OLED (Organic Light Emitting Diode): A type of display becoming popular in DAP devices as it uses very little power and creates light thus no back light is needed. The major disadvantage is that OLED displays can have low visibility in bright light as they are transmissive and not reflective.

PMP (Portable Media Player): As above, see DMP. A more current acronym than DMP.

Power Cycle: The process used to turn your player off and then on again.

QVGA (quarter-VGA): A resolution of a display found on some new high end DAP players, characteristic of 320x240.

SSD (Solid State Drives): A type of digital memory stored on chips within a casing that has no moving parts to get damaged. SSD memory can be put into laptops/computers/DAPs and can be changed/swapped etc. SSDs use the same interface as HDDs making them easy to replace and the newest models do not need power to retain memory, for more info look here.

Tactile Buttons: A mechanical button that has feel and sensation to the touch, physical characteristics like a mechanical push-button switch.

* Terabyte, petabyte, exabyte, zettabyte and yottabyte which all have the same pattern.

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Basic Player Software Terminology:

Firmware: Abbreviated as FW or fw, firmware is the software installed on your player's circuit board. It is separate from the data that goes in your player's flash memory or hard drive. Think of Firmware as the Operating System for your players, e.g. Windows, Win7, Vista, MacOS, Linux, etc. for your computer. More information here.

MSC (Mass Storage Compliant): Protocol which allows your operating system to treat your media player like a standard USB flash drive. You can drag and drop files onto the player without installing any special software. Also look here.

MTP (Media Transfer Protocol): Protocol which allows Windows Media Player, Winamp, MediaMonkey or other similar applications to sync with your player (useful for transferring DRM files to your player). Also look here.

OS (Operating System): This is the software which directly controls all of a computer or DAP/PMP's hardware components. Also look here.

OTG playlists (On-The-Go playlists): Playlists that can be created directly on the player without having to hook it up to a computer or use other software.

USB Host aka USBOTG or USB-On-The-Go: A feature that allows a player to hook up directly to another USB device such as a camera or another DAP without requiring a computer in between, allowing for the transfer of files.

Gapless: This refers to uninterrupted, seamless playback between song tracks. When music files are played back on most players, there is usually a gap or space between the end of one track and the start of the next track. DAPs/PMPs which support gapless playback allow for continuous playback of all songs with any appreciable periods of silence between tracks, e.g. live concert recordings, dance mixes, etc. It can be very annoying when listening to Pink Floyd albums for example, because some songs are meant to blend into one another. Be aware of this problem with DAPS when shopping for one.

MPEG-4: An ISO/IEC standard developed by MPEG (Moving Picture Experts Group), click here for more information.

OGG: An Open source container format. The most common codecs used are Vorbis (lossy), FLAC (lossless), Speex (for speech) and Theora (video). File extension: .ogg

Playlist: A playlist is a selection of custom-ordered songs created in digital audio programs. Many DAP’s or multimedia players for your pc support playlists. They help you organize and manage the various music files on your computer by controlling what files are played and in what order, much like a music playlist used by radio stations. They allow a continuous play of music, more advanced program features can support fading and mixing between tracks, sorting by artist or genre, and effectively give you the ability to turn your computer into a modern jukebox.

Playlist formats:
.pls (WinAmp MPEG PlayList File) - The extension for a playlist created in Winamp that can contain MPEG audio files.
.m3u (MPEG URL file) - This extension is used to stream and MP3 file or files.
.asx (Active Streaming File - Windows Media).
.wvx/.wax (Windows Media metafiles) - When a browser downloads a file with one of these extensions from a Web site, it opens Windows MediaPlayer. Windows Media Player then locates and plays the content specified in the file.
.m2a (MPEG Archive Enhanced .M3U Playlist File)
.pla Samsung format(?), binary, Winamp and other players handle these.

Replay-gain: A procedure invented that allows players to normalize loudness for individual tracks or albums. It avoids you from having to manually adjust volume levels when playing audio files from albums that have been mastered at different Loudness levels. It is supported by a large number of audio players, DAP’s and PMP’s. Basically the gain value and the peak value are then stored as metadata in the audio file, allowing ReplayGain-capable audio players to automatically amplify the signal on a per track or per album basis. Various software that offers implementation, Links: here, here and here.

Sync: Short for synchronize. When you sync a device, such as a cell phone, PDA, or DAP, etc, you synchronize it with data on your computer so that the contents are identical.

AB, AB Test: Less rigourous than an ABX test, an AB test of two audio devices or to AB two audio devices is to compare two audio devices with each other to try to ascertain their sound quality. To AB two MP3 players, for example, one should load identical files, turn off all signal processing, try to set the volume so that the volume from the headphones are as closely matched as possible, and use one pair of headphones or two identical pairs of headphones to listen to the identical files.

ABX, ABX Test: A type of double-blind listening test used to eliminate the placebo effect.

Bone Conduction: Phenomenon whereby an IEM user can hear noise (caused by body motion such as eating and walking) transmitted within the body to the acoustic chamber of the ears while wearing IEM's or custom ear monitors. The transmission or conduction of sound to the inner ear through the bones of the skull.

Burn-In (Equipment): A controversial topic and unproven theory, burn-in refers to using an audio device as part of a music-reproduction chain for a period of time before actually using that device to listen to music. Believers of burn-in claim a perceivable improvement in sound quality. This is just an outright misunderstanding of electronics, no one knows how this belief started but it could just be a misunderstanding or confusion between burn-in and warm-up.

Burn-in (headphones/iem’s): The unproven theory that with use the diaphragms of dynamic headphones become more flexible and vibrate more freely, thus changing the sound quality. To burn in a pair of headphones for example, one might connect it to an MP3 player and play some music, pink noise or white noise through the headphones for a number of hours before actually using the headphones to listen to music. There are some people who believe this theory and some who don’t. I do believe that some phones may settle in better than others and that the sound quality may or may not improve but why speed this process along the way, why not just use them and enjoy. BTW armatures used in iem’s or custom monitors do not change over time.

Clipping: A form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its published ratings, read more here.

Crossfeed: A feature on amps that blends the left and right stereo channels slightly, reducing the extreme channel separation which is characteristic in headphone listening. It is also supposed to improve soundstage, like listening to a pair of speakers.

Earbuds: Small size headphones placed directly outside of the ear canal, typically do not have a strap over the head, but lately there have been some released with straps over the hear or even around the back of head/neck.

EQ: Short for equalizer or graphic equalizer; a tool used in audio systems that allows adjustments of a given set of frequency bands, giving the listener the ability to change the relative levels of specific low, medium or high-range sounds in a mix of music or other audio.

Frequency Response: FR is a measurement of output (audio frequency) from headphones or speakers that represents their ability to reproduce sound frequencies; this property is measured in hertz (symbol Hz). For example: in theory a perfect linear headphone would have no harmonic peaks, which is highly unlikely. On the left hand side of the graph is amplitude (dBr) and along the bottom is frequency in Hertz (Hz). Along the left hand side of the line is bass and on the right side is treble. If it’s high on the left side and low on the right side then the headphones would be more towards bass heavy. The reverse is also applicable, if the line is higher on the right side and lower on the left side, they the headphones would have more emphasis on the treble, making them brighter. Further information can be found: here, here, here, here and here.

Headphones: Small speakers or speaker suspended in a housing with pads for ear comfort/protection, connected via a strap over the users head covering both ears. Keep in mind that there are single sided headphones on the market as well, but not for our purpose here. Headphones are connected to a source like a digital audio player (DAP), CD player, radio or amp which allows the user to listen privately. There are two styles: open & closed housing, “Open Style” - leaks sound out of the grills, typically have a wide soundstage, do not isolate the user from ambient sound and can be heard by others. “Closed Style” - have a sealed housing, tighter soundstage, isolate ambient sound, stronger bass and possible negative effect of distorting sound in certain frequencies due to resonances within the housing. Circumaural Circular or ellipsoid housing with earpads that completely surround around the ears. Supra-aural have pads that sit on top of the ears, rather than around them. Headphones are also referred to as - cans, sterophones, headsets, earphones, phones etc. Studio monitor headphones - Headphones designed to have a flat frequency response.

Headstage: A user's (listener's) perception of the musical soundstage while listening to headphones. "Soundstage,” is the illusion of placement and distance of sounds in a 3d-space. Headstage is not really in my vocabulary as I normally just say "soundstage," but I do see it written in some reviews.

IEM: In-ear Monitor or canalphones are headphones that are inserted directly into the opening of the ear canal. When sealed correctly they can create a high level of isolation and can be listened to at lower volume levels (available in universal or custom fit).

Impedance: A measure for the manner and degree a component resists the flow of electrical current if a given voltage is applied. It is denoted by the symbol Z and is measured in ohms. In regards to DAP’s; the lower the headphones impedance the easier they are to drive and less battery juice that you will use. Although lower impedance headphones seem to show the limitations of a DAP by making it easier to hear their system noises, like a hissing sound. The reverse applies with higher impedance headphones; they are harder for a DAP to drive, use more battery juice but at the same time hide the system hiss and sound better. With lower impedance headphones that allow you to hear hiss either an impedance adaptor or a good portable headphone amp can normally remove that. For more info on impedance look here.

Microphonics or Cable noise: A noise transmitted by the cable into the IEM heard in the ear. Properly wearing iem’s creates a seal with the ear canal and this creates a mini acoustic chamber, thus if your iem’s have poor quality cable they can transmit noise from anything touching the cable, such as it brushing against your clothing or anything else. To eliminate or reduce this bothersome noise you can wear the cable up over the ears and down the back inside of your shirt, which helps tremendously on most cables.

Noise Cancelling:

- Active Noise Cancelling - (ANC) is a method of eliminating ambient sound through electronics. Headphones are fitted with a miniature microphone in each earcup that 'listens' to external sounds/noise before it reaches your ears. The unwanted ambient sound is compared to the sound you wish to hear, whether music or silence, then the technology generates a mirror image of the unwanted sound to cancel out much of the unwanted noise. Keep in mind that this method requires batteries.

- Passive Noise Canceling - Achieved by blocking ambient noise from the outside world by either covering the whole ear with closed headphones or by blocking the inner ear canal from outside sound waves with good sealing iem’s, similar to plugging your ears with your fingers. Good to know that passive headphones do not require batteries.

Placebo Effect: Similar to an optical illusion, the placebo effect tricks listeners into believing that they hear an increase or decrease in sound quality. The best way to eliminate the placebo effect is with a double-blind listening test such as with an ABX test. More information: http://www.skepdic.com/placebo.html

Sensitivity (loudness): A measure of headphone efficiency in dBs SPL per milliwatt of input. A low number means that the headphones need more power to sound as loud as those which have a higher sensitivity. Headphones for portables need to be fairly sensitive because of the lower power output of portable stereos. Modern dynamic headphones have sensitivity ratings of 90 dB or more. When shopping for portable headphones, look for a sensitivity rating of 100 dB or greater (quoted from the HeadWize library here).

SNR (Signal to Noise Ratio): A quantity in dB that gives the estimated DAC (digital analog converter) performance of a DAP, the higher the number the more dominant the sound is over system noise and harmonics.

Soundstage: The area between two speakers that appears to the listener to be occupied by sonic images. Like a real stage, a soundstage should have width, depth, and height.

Sound Quality: (SQ or sq): When we use the term "sound quality" here we are most likely referring to the audio output or the degree of accurate sound reproduction of either digital audio players (DAP), portable media player (PMP), headphones/IEM’s or other electronic devices being discussed.

SS or ss: Abbreviation for Sound Signature.

Stereo Imaging: Audio jargon used for the aspect of sound recording and reproduction relating to spatial locations of the performers, both sideways and in depth. For example a well-made stereo recording, properly reproduced, should provide good imaging within the front quadrant; a well-made Ambisonic recording, properly reproduced, can offer good imaging all around the listener and even including height information, although the later is not really achievable with headphones IMO unless it’s perceived from a holophonic recording like Pink Floyd’s "The Final Cut" and various others and that may very well be me suffering placebo

Bootloader
A bootloader is a small piece of code (usually installed to flash memory) who's only job is to find and start up a copy of Rockbox found on the hard drive. On iriver devices, for instance, the original factory firmware file is patched with a custom Rockbox bootloader and then installed to flash memory. Rockbox itself resides entirely on the hard drive of the player.

Release: The release version is the latest stable release, free of known critical bugs. For a manual install, the current stable release of Rockbox is available at http://www.rockbox.org/download/.

Development Build: The Development build is built at each source code change to the Rockbox SVN repository and represents the current state of Rockbox development. This means that the build could contain bugs but most of the time is safe to use. For a manual install, you can download the development build from http://build.rockbox.org/.

Archived Build: In addition to the release version and the current build, there is also an archive of daily builds available for download. These are built once a day from the latest source code in the SVN repository. For a manual
install, you can download archived builds from http://www.rockbox.org/daily.shtml.

OF: Original/Old Firmware. The firmware that was in place on your player before Rockbox replaced it.

Patch: A set of source code changes as produced with the diff tool. To apply a patch, you first need to have a development environment setup and working. See Working With Patches for more information.

Root: The root directory is the main directory. For example, the root directory of the C drive is "C:\".

Rockbox Utility: The is the automated installer tool for Rockbox available here.

WPS: Initialization of While Playing Screen. The screen that is shown while a song is playing. You can use a Custom WPS (see also the WPS Gallery for inspiration). You can of course leave the screen while the song is playing, but you can only see the WPS while actually playing a song

Rockbox Target Classifications:

- Stable Target Criteria -

A main Rockbox build that enables the device to be used as a digital music player. Rockbox does not support charging or USB on every player, and in those cases the port must support dual-booting into the original firmware to enable those features.

End-user installation instructions for the three major operating systems (Linux, OS X and Windows), including instructions for dual-boot where it is required to meet the previous criteria;

A released bootloader

Binary releases of any required installation tools (for all three major OSes).

Buildable through the build system

- Unstable Target Criteria -

Generally usable for audio playback as determined by target's developers

Well documented install procedure on wiki

Well organized wiki explaining the current state of the port (see SansaAMS for example)

A released bootloader

Binary releases of any required installation tools for one or more OSes.

- Unusable Target Criteria -

Targets which are well on their way to being unstable, but still with major issues.

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Miscellaneous Terminology:

Bluetooth: An industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, digital audio players, headphones, laptops, PCs, printers, digital cameras, video game consoles, etc… over a secure, globally unlicensed short-range radio frequency.